Acceleration of cyanobacterial dominance in north temperate‐subarctic lakes during the Anthropocene

Abstract

Increases in atmospheric temperature and nutrients from land are thought to be promoting the expansion of harmful cyanobacteria in lakes worldwide, yet to date there has been no quantitative synthesis of long-term trends. To test whether cyanobacteria have increased in abundance over the past ~ 200 years and evaluate the relative influence of potential causal mechanisms, we synthesised 108 highly resolved sedimentary time series and 18 decadal-scale monitoring records from north temperate-subarctic lakes. We demonstrate that: (1) cyanobacteria have increased significantly since c. 1800 ce, (2) they have increased disproportionately relative to other phytoplankton, and (3) cyanobacteria increased more rapidly post c. 1945 ce. Variation among lakes in the rates of increase was explained best by nutrient concentration (phosphorus and nitrogen), and temperature was of secondary importance. Although cyanobacterial biomass has declined in some managed lakes with reduced nutrient influx, the larger spatio-temporal scale of sedimentary records show continued increases in cyanobacteria throughout the north temperate-subarctic regions.

Tracking past changes in lake-water phosphorus with a 251-lake calibration dataset in British Columbia: tool development and application in a multiproxy assessment of eutrophication and recovery in Osoyoos Lake, a transboundary lake in Western North America

“…This typically includes increases in algal biomass, including cyanobacteria blooms which are recognized as a threat to water quality worldwide (O'Neil et al, 2012). Similar to overall algal production, the factors most strongly related to increases in cyanobacteria are nutrients and temperature (Jöhnk et al, 2008;Kosten et al, 2012;Taranu et al, 2012;Beaulieu et al, 2013), as well as lake depth (Taranu et al, 2015).…”

Urban point sources of nutrients were the leading cause for the historical spread of hypoxia across European lakes

“…Multiple sites need to be investigated to quantify a regional trend, as well as to evaluate local to regional heterogeneities. Only a few studies have interpreted the long-term trajectories of lakes (based on >100-year lake records) in terms of eutrophication on a regional scale by analyzing trends in nutrient and dissolved CO 2 concentrations (13,14), carbon burial rates (15), cyanobacterial dominance (16), and hypoxia development (17). However, only one of these studies (13) considered the temporal dynamics of land cover and use, and only a few studies (16,17) considered modern land cover.…”

“…Only a few studies have interpreted the long-term trajectories of lakes (based on >100-year lake records) in terms of eutrophication on a regional scale by analyzing trends in nutrient and dissolved CO 2 concentrations (13,14), carbon burial rates (15), cyanobacterial dominance (16), and hypoxia development (17). However, only one of these studies (13) considered the temporal dynamics of land cover and use, and only a few studies (16,17) considered modern land cover. Our current lack of knowledge of the effects arising from cumulative environmental pressures presents the potential for serious underestimation of the long-term impacts of land use changes and hinders our ability to identify the relative importance of P sources to lake ecosystems (18).…”

Evaluation of a Modified Monod Model for Predicting Algal Dynamics in Lake Tai

“…Besides temperature, TN, and TP, other factors, such as nitrogen-to-phosphorus ratio [31], anoxia and ferrous iron [32], and climate change [33,34], have been found to affect cyanobacterial dynamics/blooms in lakes. However, limited by data availability, our study could not evaluate prediction performance of the modified Monod model when either of those other factors is used as independent variable s in Equation (4).…”